Grinding machine for bearing rings and method for adjusting such a machine

Abstract

A grinding machine for bearing rings, the machine includes a frame, a rotating grinding wheel movable in rotation around a first rotation axis, a working station where a bearing ring stands during a grinding operation of one of its surfaces and holding means for holding a bearing ring in the working station, these holding means being rotatable around a second rotation axis and supported by a support plate movable with respect to the frame. The machine includes a first electric actuator for moving the support plate in rotation with respect to the frame, around a third axis perpendicular to the first and second rotation axes and a second electric actuator for moving the holding means in translation along the second rotation axis.

1 . A grinding machine for bearing rings, this machine including:
 a frame,   a rotating grinding wheel movable in rotation around a first rotation axis,   a working station where a bearing ring stands during a grinding operation of one of its surfaces   a holding subsystem for holding a bearing ring in the working station, the holding subsystem being rotatable around a second rotation axis and supported by a support plate movable with respect to the frame,   wherein the machine includes:
 a first electric actuator for moving the support plate in rotation with respect to the frame, around a third axis perpendicular to the first and second rotation axes, and 
 a second electric actuator for moving the holding subsystem in translation along the second rotation axis. 
   
     
     
         2 . The grinding machine according  claim 1 , the first electric actuator further comprising a first electric motor rigidly connected to the support plate, wherein an output shaft of the first electric motor drives a screw member engaged in a threaded hole of a reference part rigidly connected to the frame and in that the output shaft of the first electric motor is perpendicular to the third axis. 
     
     
         3 . The grinding machine according to  claim 2 , further comprising a position sensor located next to the first electric motor and configured to detect the position of the motor with respect to the reference part. 
     
     
         4 . The grinding machine according to  claim 2 , wherein a first distance, measured radially with respect to the third axis between the axis and the output shaft of the first engine, is at least five times larger than a second distance, wherein the second distance is measured radially with respect to the third axis between the third axis and a chuck which belongs to the holding subsystem and is in contact with a bearing ring in the working station. 
     
     
         5 . The grinding machine according to  claim 2 , wherein a first distance, measured radially with respect to the third axis between the axis and the output shaft of the first engine, is at least ten times larger, than a second distance, measured radially with respect to the third axis between the third axis and a chuck which belongs to the holding subsystem and is in contact with a bearing ring in the working station. 
     
     
         6 . The grinding machine according to  claim 1 , the second electric actuator further comprising:
 a second electric motor mounted on the support plate; and   a movement converter mounted on the support plate,   wherein the movement converter is driven by an output shaft of the second electric motor, the movement converter being configured to convert a rotation movement into a translation movement.   
     
     
         7 . The grinding machine according to  claim 5 , the movement converter further comprising a ball-screw mechanism. 
     
     
         8 . The grinding machine according to  claim 5 , wherein the output shaft of the second electric motor is perpendicular to the second rotation axis and connected to the movement converter via a worm screw mechanism. 
     
     
         9 . A method for automatically adjusting the position of the bearing rings in the working station of a grinding machine with respect to a grinding wheel of the grinding machine, depending on at least one of the profile of an edge of the grinding wheel and the dimensions of the bearing ring,
 accessing the grinding machine the grinding machine comprising:
 a frame, 
 a rotating grinding wheel movable in rotation around a first rotation axis, 
 a working station where a bearing ring stands during a grinding operation of one of its surfaces 
 a holding subsystem for holding a bearing ring in the working station, the holding subsystem being rotatable around a second rotation axis and supported by a support plate movable with respect to the frame, 
   wherein the machine includes:
 a first electric actuator for moving the support plate in rotation with respect to the frame, around a third axis perpendicular to the first and second rotation axes, and 
 a second electric actuator for moving the holding subsystem in translation along the second rotation axis; 
   the method comprising steps of:   a) accessing a memory where angular offset values are stored, for an angle measured between the first rotation axis and the second rotation axis for at least one of different edge profiles and different bearing ring dimensions;   b) selecting an angular offset value in the memory, as a function of at least one of the profile of the edge and of the bearing ring dimensions; and   c) piloting the first electric actuator in order to obtain the selected angular offset value between the first and second rotation axes.   
     
     
         10 . A method according to  claim 8 , further comprising steps of:
 d) grinding a bearing ring with the grinding wheel;   e) determining the position of a ground zone of the bearing ring with respect to a front face and a back face of the bearing ring   f) assessing if the grinding ring has to be moved axially, along the second rotation axis, in order for the ground zone to be centered between the front and back faces and, if yes, to what extent; and   g) piloting the second electric actuator in order to move the holding means in accordance with the findings of step f).   
     
     
         11 . A method according to  claim 8 , further comprising steps of:
 d) moving the holding means along the second rotation axis, in a direction away from the grinding wheel;   e) driving the grinding wheel in rotation around the first axis;   f) moving the grinding wheel in a direction perpendicular to the first rotation axis in order to align, along the second rotation axis, a lateral face of the grinding wheel with a chuck which belongs to the holding means and is configured to be normally in contact with a bearing ring in the working station;   g) piloting the second electric actuator to move the chuck towards the lateral face of the grinding wheel, in translation along the second rotation axis;   h) detecting a contact between an axial face of the chuck and the lateral face of the grinding wheel;   i) piloting the first electric actuator to stop the translation movement of step k) as soon as a contact is detected in step l); and   j) piloting the first electric actuator to move the chuck still towards the lateral face of the grinding wheel on a given stroke, which provokes a grinding operation of the axial face of the chuck.   
     
     
         12 . A method according to  claim 10 , wherein in step l) a contact between the axial face of the chuck and the lateral face of the grinding wheel is detected via the rotation of a shaft integral in rotation with the chuck.